Frequently Asked Questions

The standard UV Index measures sunburn risk, but your body needs a specific type of UV (UVB) to make Vitamin D. When the sun is too low in the sky, the atmosphere filters out almost all UVB. Our custom Vitamin D Index calculates both the overall UV strength and the precise angle of the sun to tell you exactly when those crucial UVB rays are reaching the ground.

• 0: No Vitamin D is produced. The sun is too low or conditions block the UVB you need.
• 0–1: Very negligible. The sun is too low or blocked by clouds; only a tiny amount of Vitamin D may be produced.
• 1 and above: Your Vitamin D window is open! Conditions have crossed the threshold to start producing Vitamin D. The higher the number climbs, the faster your body synthesizes it.

The standard UV Index mostly measures UVA rays (which cause skin aging and sunburns). If you only look at the UV Index in the early morning or late afternoon, you might think you are getting Vitamin D, but the atmosphere is actually blocking the UVB rays you need. The Vitamin D Index prevents this confusion.

Healthy Weather displays the US EPA Air Quality Index (AQI), the most widely used standard internationally. It runs on a scale from 0 to 500, with categories ranging from “Good” to “Hazardous.” If you are used to the European Air Quality Index (EAQI), note that the numbers and thresholds differ — for example, a US AQI of 50 (“Good”) does not equal a European AQI of 50.

Our Vitamin D Index and health metrics use our own calculations. Weather, UV, air quality, and pollen data are powered by Open-Meteo.

Different weather apps use different data sources and weather models. A small difference in temperature (around 1°C) or humidity is completely normal and expected. Neither is wrong — they just use different methods and accuracy levels to calculate the weather at your location.

We continuously refine and expand our data sources in the background to keep your weather data as accurate as possible.

Healthy Weather is an iOS app built around how weather and your environment affect wellbeing. It layers health-related weather insight — especially our Vitamin D Index for Vitamin D timing and sun safety — with environmental signals like air quality and pollen, alongside everyday conditions so you can plan with context, not just temperature and icons.

Healthy Weather is a premium, ad-free tool designed to give you useful health-related weather and environmental information without tracking or selling your information. You get your first 2 weeks completely free to explore the Vitamin D Index, interactive charts, and allergy tracking. After that, it requires a simple subscription to keep access.

Healthy Weather works in all regions worldwide. Weather, UV, Vitamin D Index, and air quality data are available globally. Pollen tracking is currently limited to Europe due to data availability. The app uses your device location to show local, health-focused forecasts.

No. We currently only support device location — there is no manual location input.

No. Healthy Weather is a planning tool — not a medical device. All data, including Vitamin D windows, UV forecasts, air quality, and pollen levels, is for general information only. It can help you make better decisions, but it is not a substitute for professional medical advice or your own judgment.

You are ultimately responsible for how you act on the information. The app cannot account for your personal health situation, skin type, medications, or local conditions, and data may occasionally be inaccurate due to technical bugs or third-party outages. Always consult a doctor if you have concerns about sun exposure, allergies, or any health condition.

The developer is not liable for any health issues resulting from the use of this app. For the full legal terms, see our Terms of Use.

We understand that a single app might not give you all the weather data you want, so Healthy Weather makes it simple to jump to another app with one tap.

A few popular apps are already listed in Settings for convenience. If the app you want isn’t listed, you can enter any custom URL in Settings. Two types of links work:

• Universal Links look like a regular website URL (e.g. https://example.com). If the app is installed, iOS opens it directly. If not, it opens the website in Safari as a fallback. Not every app supports Universal Links — it’s up to each app’s developer to enable them.
• URL Schemes are custom app addresses like appname://. These open the app directly but have no web fallback — nothing happens if the app is not installed. Most apps support this.

To find the right link for an app: search online for “[App Name] iOS URL scheme”, or check the app’s own website or developer documentation. Not sure? Contact us and we’ll help you find the right link.

The linked app must be installed for URL scheme links to work. All trademarks belong to their respective owners. Healthy Weather is not affiliated with any third-party apps.

We have no plans for Android unless there is significant demand.

Use the links in the app under Settings → Feedback (e.g. Report a Bug, Request a Feature, Contact the Developer). You can also reach us via the Support page on our website. We read all messages and use them to improve Healthy Weather.